Translation guide
In Japanese, the word for 'father-in-law' depends on whose father you are referring to (your spouse's father vs. your own father in a legal sense) and the social context. The most common and neutral term is 義理の父, but in daily conversation, people often use お義父さん or simply お父さん when addressing their spouse's father directly.
My father-in-law is a doctor.
More formal and written term for father-in-law. Can also mean stepfather or adoptive father, so context is important.
My relationship with my father-in-law is good.
Traditional term for father-in-law (specifically wife's father from the husband's perspective, or husband's father from the wife's perspective). Rarely used in modern conversation; may appear in literature or historical contexts.
Go to greet my father-in-law at his house.
What to call your spouse's father when speaking to him.
Polite and common way to address your father-in-law directly. Uses the same reading as 'father' but with the honorific prefix お and the kanji 義 (meaning 'in-law'). In writing, it may be seen as お父さん when context makes the relationship clear.
Father-in-law, would you like some tea?
Many Japanese people simply call their father-in-law お父さん (dad) once they are married, especially in casual family settings. This is very common and natural, but can be ambiguous without context.
Talking about your own father-in-law to someone outside the family, using humble language.
When speaking to outsiders, you refer to your father-in-law humbly as 義父. This is the standard humble term.
My father-in-law is always indebted to you.
Talking about another person's father-in-law respectfully.
Referring to a father-in-law who is also a stepfather or adoptive father, or in legal documents.
In legal or formal contexts, 義父 can mean father-in-law, stepfather, or adoptive father. The specific meaning is usually clear from context.
legal father-in-law (or stepfather/adoptive father)
When you first meet your spouse's father, it's safe to use お義父さん. As you become closer, many families naturally shift to お父さん. Observe what your spouse calls him and follow suit.
While 義理の父 is correct, it sounds stiff in everyday conversation. When talking with friends, you might simply say お義父さん or even 旦那のお父さん (husband's father) / 奥さんのお父さん (wife's father) to be clear and natural.
Dad, you're early today.
Please give my regards to your father-in-law.